Bending the course of evolution: how mutualistic interactions affect macroevolutionary dynamics of diversification in mimetic butterflies

Evidence that species interactions can affect macroevolutionary dynamics of trait and species diversification is scarce. Mutualistic Müllerian mimicry is a compelling example of example of ecological interactions that has been shown to drive evolutionary convergence, Here, we test how mutualistic Müllerian mimicry shapes macroevolutionary patterns of diversification in the Ithomiini butterflies. We show that the age of color patterns is the primary determinant of species richness within mimicry rings but not phylogenetic diversity. We find pervasive phylogenetic signal in mimicry rings and in color patterns associated within polymorphic species. Only a small set of mimicry rings show high phylogenetic diversity. We identify patterns of saturation in the accumulation of new mimicry rings and in the number of evolutionary convergences towards the most species-rich mimicry rings. Those saturation patterns are likely caused by niche filling along various ecological dimensions, within and among the mimetic communities living in sympatry. The time-dependent effects detected in our study illustrate how neutral processes and ecological interactions interact and shape species and phenotypic diversification.